Basic Science and Technology - Junior Secondary 3 - Environmental hazard III - Flooding

TERM: 1^ST TERM

WEEK: 6

CLASS: Junior Secondary School 3

AGE: 14 years

DURATION: 40 minutes each for 2 periods

DATE:

SUBJECT: Basic Science

TOPIC: Environmental hazard III - flooding

SPECIFIC OBJECTIVES: At the end of the lesson, the learners should be able to

1. ) Define flooding
2. ) Discuss soil structure
3. ) Explain drainage and the kinds of drainage pattern
4. ) Outline the causes, effects and prevention of flooding

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, story-telling, videos from source

INSTRUCTIONAL MATERIALS: Recommended Basic Science textbooks for Junior Secondary School 3

INSTRUCTIONAL PROCEDURES: PERIOD 1-2:

NOTE

ENVIRONMENTAL HAZARD III- FLOODING

Flooding is the overflow of water onto typically dry land. It often results from heavy rainfall, rivers overflowing, storm surges, melting snow, or dam failures. Flooding can lead to widespread property damage, loss of life, and disruption to infrastructure. It is considered a natural disaster, though human activity can exacerbate its occurrence and severity.

Soil Structure

Soil structure refers to the arrangement of soil particles into aggregates, or clusters, which influence water retention, drainage, root penetration, and air movement within the soil. Good soil structure promotes healthy plant growth by enabling sufficient air, water, and nutrients to move freely. Factors such as organic matter, soil type, and compaction impact soil structure, which in turn can affect the soil's susceptibility to erosion and flooding.

Drainage and the Kinds of Drainage Patterns

Drainage refers to the process by which water flows through and off the land. Different drainage patterns emerge based on the terrain, soil type, and geological features. Common drainage patterns include:

• Dendritic: Tree-like pattern, typical on uniform soil.
• Radial: Radiates outward from a central point, usually seen on volcanic cones.
• Rectangular: Forms right angles, often due to faulted or fractured terrain.
• Trellis: Resembles a garden trellis and forms where there are alternating resistant and weak rock layers.

Each pattern influences the speed and volume of water flow, affecting an area’s susceptibility to flooding.

Causes, Effects, and Prevention of Flooding

Causes:

• Natural: Heavy rainfall, snowmelt, river overflows, coastal storm surges.
• Human-Induced: Urbanization, deforestation, poor land management, and dam failures.

Effects:

• Environmental: Erosion, loss of soil fertility, habitat destruction.
• Economic: Damage to property, infrastructure, and agricultural lands.
• Social: Displacement of communities, health risks from waterborne diseases.

Prevention:

• Improved Drainage Systems: Creating channels and gutters to manage water flow.
• Reforestation: Planting trees to help absorb rainfall and reduce surface runoff.
• Constructing Dams and Levees: Structures to control water flow and prevent overflow.
• Urban Planning: Avoiding development in flood-prone areas and implementing sustainable building practices.

EVALUATION:

1. What is flooding, and how does it impact communities and the environment?
2. Explain how soil structure influences water retention and susceptibility to flooding.
3. Describe different drainage patterns and how each affects water flow in a given area.
4. List and explain at least three major causes of flooding and discuss their environmental consequences.
5. What are some effective methods to prevent flooding, and how can communities implement these practices?

CLASSWORK: As in evaluation

CONCLUSION: The teacher marks their books and commends them positively